Hole inspection scanner system and method of use

Abstract

A system and method are provided for a scanner for controlling a removable element such as a sensor mandrel cartridge. The scanner has a housing. A first motor is secured within the housing for actuating circumferential motion for the mandrel. A second motor within the housing for actuating axial motion for the element. The scanner also includes a geartrain and shafts, the later for maintaining alignment of the geartrain. The housing provides structural support for the shafts and in turn the geartrain. The scanner may have a first encoder to record a circumferential position of the sensor mandrel and a second encoder to record an axial position of the sensor mandrel.

Description

[0001] HOLE INSPECTION SCANNER SYSTEM AND METHOD OF USE

[0002] RELATED APPLICATION

[0003] The present application claims priority under 35 U.S.C. §119(e) to U.S. provisional patent application, U.S. Ser. No. 63 / 597,321, filed November 8, 2023 which is herein incorporated by reference in its entirety.

[0004] GOVERNMENT SUPPORT

[0005] This invention was made with Government support under Contract Number FA864922P0592 awarded by the United States Air Force. The Government has certain rights in this invention.

[0006] TECHNICAL FIELD

[0007] The present disclosure relates to the field of non-destructive evaluation (NDE).

[0008] BACKGROUND

[0009] NDE can be used to evaluate the condition of materials at and during production, prior to deployment, periodically during deployment, and after deployment. In some applications, NDE of holes, such as bolt holes, is critical to determining whether a part can continue to be safely used, or if it should be repaired or replaced (or simply used less aggressively).

[0010] In U.S. Patent No. 12,061,169, issued on August 13, 2024, which is incorporated herein by reference in its entirety, Dunford et al. (hereinafter “Dunford I”) disclose a system and method for inspecting challenging material locations such as holes. The system may include a sensor cartridge (“mandrel”) for hole inspection that has a helical portion to which a sensor array is attached. The radius of the helical portion can be increased or decreased by applying a torque to the helical portion thereby allowing the sensor to be inserted into a hole or pressed against the internal wall of the hole. A scanner is described to which mandrels can be quickly connected and changed enabling an inspector to quickly switch between different mandrels (e.g., for different hole sizes and sensor configurations). Also disclosed is an inspection procedure and data processing algorithm for performing an inspection. The data processing algorithm utilizes a signature library for enhancing the detection or sizing of features of interest such as cracks. The algorithm and library can account for material edges, and various material types.

[0011] In U.S. Patent Application Publication 2022 / 0341875, published on October 27, 2022, which is incorporated herein by reference in its entirety, Chaplan et al. (hereinafter “Chaplan”) disclose a system and method for performing a hole inspection performance study. Specimens for the performance study are made from a reconfigurable set of inspection plates. Each plate includes multiple test holes which are located symmetrically. The plates may be of various thicknesses and materials. Each test hole may or may not have a feature such as a crack or machining notch. Such features may be located at various positions of the hole, such as at an edge, within the bore, and at various circumferential positions. A specimen is formed by stacking two or more plates and securing the stack together with an alignment tool. A variety of specimens may be formed by using different combinations of inspection plates and flipping and rotating the member plates. A hole inspection system is disclosed as well as an inspection procedure and data processing algorithm for inspecting each hole.

[0012] In U.S. Patent No. 10,677,756, issued on June 9, 2020, which is incorporated herein by reference in its entirety, Goldfine et al. (hereinafter “Goldfine I”) described “an integrated mandrel” for inspecting bolt holes. The mandrel included a sensor such as an eddy current array, and mechanical support to facilitate hole inspection. A handheld scanner was contemplated for use with the mandrel and a sensor was described. Goldfine I’s mandrel may include a mechanical wedge or a balloon portion that can be inflated (using gas or liquid) to apply pressure against the sensor to the bolt hole. A piston was described for actuation. Goldfine I described various scanner mechanisms to facilitate rotation of the mandrel within the bolt hole such as a slip ring scanner and the use of a spooling connection tape. A portion of the sensor measurement electronics is located on the mandrel (rotating) side while the remaining portion of the sensor measurement electronics are located on the stationary side.

[0013] In U.S. Patent No. 11,435,317, issued September 6, 2022, which is incorporated herein by reference in its entirety, Goldfine et al. (hereinafter “Goldfine II”) describes a process for enhancing detection of defects having characteristic shapes provided in a signature library. Signatures, which may be obtained from actual sensor measurements from a known defect and then correlated with sensor measurements. A large correlation may be an indication that a defect is present at the material location where the measurement data was collected. Goldfine II further describes methods for obtaining signatures for the signature library, selecting an appropriate signature from the library for data, performing single and multichannel correlation, and flagging defect detections.

[0014] In International Publication No. WO 2023 / 192887 Al, published October 5, 2023, which is incorporated herein by reference in its entirety, Dunford and Washabaugh (hereinafter “Dunford II”) disclose an eddy current sensor with a remote current sense that has a drive conductor, current sense conductor, and one or more sense conductors. The drive conductor has first and second loop portions, the current sense conductor has a third loop portion, and the sense conductor has a sense loop portion. The first and third loop portions are proximal to each other to form the remote current sense. The sense loop portion and the second loop portion are proximal to each other to form a sense element. The remote current sense and sense element are suitably distant from one another to have separate environments of sensitivity. The sensor may be used by collecting transimpedance measurements from both the remote current sense and sense element under known conditions, and with the sense element under unknown conditions. These measurements are combined to provide a calibrated measurement result suitable for further analysis.

[0015] In U.S. Patent No. 6,188,218, issued February 13, 2001, which is herein incorporated by reference in its entirety, Goldfine et al. (hereinafter “Goldfine III”) describe calibration of an eddy current sensor “in air.”

[0016] In U.S. Patent No. 10,324,062, issued June 18, 2019, which is herein incorporated by reference in its entirety, Denenberg et al. (hereinafter “Denenberg”) describe a fully parallel, multi-channel impedance instrument.

[0017] In U.S. Patent No. 6,784,662, issued August 31, 2004, which is herein incorporated by reference in its entirety, Schlicker et al (hereinafter “Schlicker”), describes an eddy current sensor array.

[0018] In U.S. Patent No. 7,467,057, issued December 16, 2008, which is herein incorporated by reference in its entirety, Sheiretov et al (hereinafter “Sheiretov”), describes material property estimation using non-orthogonal responsive databases.

[0019] SUMMARY

[0020] One aspect relates to a scanner for controlling a removable element, the scanner comprising: a housing; a first motor secured within the housing for actuating circumferential motion for the mandrel; a second motor within the housing for actuating axial motion for the element; a geartrain comprising a plurality of gears; and a plurality of shafts for maintaining alignment of the geartrain, wherein the housing provides structural support for the plurality of shafts. Some embodiments further comprise, a first encoder to record a circumferential position of the element; and a second encoder to record an axial position of the element. Some embodiments further comprise a solenoid to further control the element.

[0021] The foregoing is a non-limiting summary of the invention, which is defined by the attached claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are not intended to be drawn to scale. In the drawings, each identical or nearly identical component that is illustrated in various figures is represented by a like numeral. For purposes of clarity, not every component may be labeled in every drawing. In the drawings:

[0023] FIG. 1 A is block diagram of a system for inspecting a test object, according to some embodiments;

[0024] FIGs. 1B-C show eddy current array sensors, according to some embodiments;

[0025] FIG. 2 is a block diagram of an instrument for measuring and analyzing sensor measurements, according to some embodiments;

[0026] FIG. 3 A shows a block diagram of a system 310 for hole inspection according to some embodiments;

[0027] FIG. 3B shows a test object with a hole having a 3 layer stackup, according to some embodiments;

[0028] FIG. 3C; shows a system 310 having a handheld instrument, external flex-cable, and handheld scanner, according to some embodiments;

[0029] FIG. 3D shows a block diagram of a motion control board, according to some embodiments;

[0030] FIGs. 4A-4D show embodiments of external flex-cable 320, according to some embodiments;

[0031] FIGs. 5A - 5H show views of a handheld instrument 400, according to some embodiments;

[0032] FIG. 51 shows a perspective view of a handheld instrument 400 without protective boot 401, highlighting housing 470 and external components, according to some embodiments;

[0033] FIGs. 51 and 5K sealed housing 470 and internal components of handheld instrument 500, according to some embodiments.

[0034] FIG. 6A shows a block diagram of handheld instrument 400 and internal components, according to some embodiments;

[0035] FIG. 6B shows a block diagram of an auxiliary board 440 of handheld instrument 400, according to some embodiments;

[0036] FIGs. 7 shows a view of another handheld instrument 500, according to some embodiments;

[0037] FIGs. 8A-8I show several views of handheld scanner 300 including installation of mandrel cartridge 300, according to some embodiments; FIGs. 9A-9D show shuttle assembly 670, an integral feature of scanner 300, according to some embodiments;

[0038] FIGs. 10A-10C show shuttle assembly 670 and geartrain 640, integral features of scanner 300, according to some embodiments;

[0039] FIG. 11 shows additional detailed features and components of scanner 300, according to some embodiments;

[0040] FIGs. 12A-12C show details of drive gear 617 of scanner 300, according to some embodiments;

[0041] FIGs. 13A-13B show upper chassis 660 of scanner 300, according to some embodiments;

[0042] FIGs. 14A-14B show internal scanner cable 608, according to some embodiments;

[0043] FIG. 15 shows additional views of geartrain 640 of scanner 300, according to some embodiments;

[0044] FIG. 16 shows additional views and details of scanner 300, according to some embodiments;

[0045] FIGs. 17A-17C show mandrel 700, according to some embodiments;

[0046] FIG. 18 shows structural components of mandrel 700, according to some embodiments;

[0047] FIG. 19 shows sensor components of mandrel 700 including the sensor active area 706, wrapping lead 707, and sensor connector 708.

[0048] FIGs. 20A-20D show helical elements 704 of mandrel 700, according to some embodiments; and

[0049] FIG. 21 is a flow diagram of a method which is used in some embodiments for inspecting holes, according to some embodiments.

[0050] DETAILED DESCRIPTION

[0051] Non-destructive inspection of materials is critical for many applications, but such inspections can be challenging because of object geometry, material, and access issues. The inventors have recognized and appreciated the need for improved inspection procedures and equipment with which to perform such challenging inspections.

[0052] An example of a challenging inspection application is hole inspection such as for holes used for bolts and other fasteners. For applications in which an unfilled hole can be inspected directly (e.g., without the fastener installed) there is an opportunity to provide a high resolution inspection of the hole for a variety of features such as defects.

[0053] A system and method are provided for inspecting challenging material locations such as holes. The system may include a scanner and a sensor cartridge (“mandrel”) for inspecting holes with a sensor technology that may generally perform better where the sensor is in close proximity to the wall of the hole, such as an eddy current sensor. Different mandrels may be provided for different hole sizes and different sensor configurations. Also disclosed is an inspection procedure and data processing algorithm for performing an inspection. Some aspects relate to a scanner with motors for both axial and circumferential motion, procedures for automated inspection using these two motors, plus actuation of the mandrel to coordinate expansion and contraction during insertion and inspection, redesign of the sensor cartridge to make it compact and easy to remove and reinstall along with use of an intermediate flex cable in the scanner that enables the use of the compact cartridge and an external flex cable that allows the scanner and inspection to be performed at a significant distance of 4ft or more from the instrument and computer, use of data from a complete scan to perform a second scan at a different resolution or location axial in the hole to improve detection performance and discrimination between cracks and other anomalies or edge effects, and use of machine learning or other common artificial intelligence methods (ML / Al) to train the algorithms as a complement or replacement for the use of signature libraries disclosed in prior inventions, where the ML / Al is first trained on a set of simulated or actual defects using the scanner and then an inspection is performed using the trained algorithm. Furthermore, inspection data from prior inspections may be used to further enhance the performance of the defect detection and reduce false indications.

[0054] The remainder of the Detailed Description is organized as follows. Section I provides an overview of an inspection system. Section II describes some embodiments of the impedance instrumentation that may be used for the bolt hole inspection system or other applications. Section III describes a handheld scanner that may be used for hole inspection. Section IV describes an improved mandrel sensor cartridge. Section V provides a procedure for inspecting holes and other test objects using the inspection system. Finally, Section VI provides a closing discussion.

[0055] Section I - System Overview

[0056] Aspects of some embodiments relate to the use of a system 100 for inspecting a test object 130. System 100 is shown as a block diagram in FIG. 1A. System 100 includes an instrument 110 and a sensor cartridge 140. In some embodiments, system 100 includes a scanner 150 for providing mechanical support for instrument 110, sensor cartridge 140, and / or test object 130 as well as facilitating relative motion between sensor cartridge 140 and test object 130.

[0057] Instrument 110 may be housed in a housing 107; in some embodiments the housing is substantially cylindrical in shape such as that described in U.S. Patent No. 10,416,118, Measurement system and method of use, by Goldfine et al. issued September 17, 2019 and herein incorporated by reference in its entirety (hereinafter “Goldfine IV”). Sensor cartridge 140 may have a rigid connector which interfaces both mechanically and electrically with an instrument side connector 105.

[0058] In some embodiments, sensor cartridge 140 is connected to instrument side connector 105 via cable 180, passing data, power, and communication along conductors 321. Cable 180, shown in FIGS. 4A-4D may be of arbitrary length in accordance with the requirements of the application. Although cable 180 is shown with only excitation signals 181 and response signals 183 passing through it, it should be appreciated that cable 180 may also convey other signals (including power). For example, power and / or measurement signals for position encoder 103 may be conveyed through cable 180. Similarly, power and / or control signals for actuator 101 may be conveyed through cable 180. Cable 180 may include a protective covering 325 that is flexible enough to enable inspection for the features of interest and durable enough to prevent kinking, impact damage, tearing and other such failure or damage modes. Cable 180 may also have rigid housings 323 to protect the connector and maintain connection. These housings may be of clamshell design clamping around the connectors 322. Cable 180 may also include mechanical strain relief 324 at each connecting end, and clamshell housing 323 may clamp strain relief and protecting covering the alleviate any mechanical strain on cable. Cable 180 may include mechanical connections 326 to remove strain from the connectors and conductors. Strain relief may extend beyond the clamshell housings to provide mechanical support to the cable where it is contained by the clamshells. Cable 180 conductors 321 may be discrete wires or flexible printed circuit. Cable 180 may have bends 327 in housing 323 to support use of flexible printed circuit construction.

[0059] In some other embodiments, sensor 120 is directly connected to instrument side connector 105. Sensor cartridge 140 in some embodiments also includes a flexible sensor 120, and a mechanical support 141 to which the sensor is attached. Sensor 120 may be attached to mechanical support 141 with glue, tape, double sided tape, or in any suitable way. In some embodiments, sensor 120 is integrally manufactured with mechanical support 141. For example, electrical traces of sensor 120 may be printed (or otherwise formed) directly on mechanical support 141 and possibly buried within mechanical support 141 by adding additional material of mechanical support 141 over such traces. Instrument 110 is configured to provide excitation signals 181 to sensor 120 and measure the resulting response signals 183 of sensor 120. Response signals 183 may be measured and processed to estimate properties of interest, such as electromagnetic properties (e.g., electrical conductivity, permeability, and permittivity), geometric properties (e.g., layer thickness, sensor liftoff), material condition (e.g., fault / no fault, crack size, layer to layer bond integrity, porosity, residual stress level, temperature), or any other suitable property or combination thereof including properties of the fabricated part and the powder. (Sensor liftoff is a distance between the sensor and the closest surface of the test object for which the sensor is sensitive to the test object’s electrical properties.) This may include qualification of a repair process for a hole, by inspecting the hole before and after the repair process to guide the repair process by measuring features of the damage such as location and depth estimation and to verify the repair was performed properly and without defects. This may include detection of damage such as corrosion pitting, exfoliation, heat damage, or mechanical damage or poor machining or fretting damage. This may also provide a means for inspection coldwork (expansion for the purpose of adding compressive residual stresses) quality for holes through geometry or property measurements.

[0060] Instrument 110 may include a processor 111, a user interface 113, memory 115, an impedance analyzer 117, and a network interface 119. Though, in some embodiments of instrument 110 may include other combinations of components. While instrument 110 is drawn with housing 107, it should be appreciated that instrument 110 may be physically realized as a single mechanical enclosure; multiple, operably-connected mechanical enclosures, or in any other suitable way. For example, in some embodiments it may be desired to provide certain components of instrument 110 as proximal to sensor 120 as practical, while other components of instrument 110 may be located at greater distance from sensor 120.

[0061] Processor 111 may be configured to control instrument 110 and may be operatively connected to memory 115. Processor 111 may be any suitable processing device such as for example and not limitation, a central processing unit (CPU), digital signal processor (DSP), controller, addressable controller, general or special purpose microprocessor, microcontroller, addressable microprocessor, programmable processor, programmable controller, dedicated processor, dedicated controller, or any suitable processing device. In some embodiments, processor 111 comprises one or more processors, for example, processor 111 may have multiple cores and / or be comprised of multiple microchips. Processing of sensor data and other computations such as for control may be performed sequentially, in parallel, or by some other method or combination of methods.

[0062] Memory 115 may be integrated into processor 111 and / or may include “off-chip” memory that may be accessible to processor 111, for example, via a memory bus (not shown). Memory 115 may store software modules that when executed by processor 111 perform desired functions. Memory 115 may be any suitable type of non-transient computer-readable storage medium such as, for example and not limitation, RAM, a nanotechnology-based memory, optical disks, volatile and non-volatile memory devices, magnetic tapes, flash memories, hard disk drive, circuit configurations in Field Programmable Gate Arrays (FPGA), or other semiconductor devices, or other tangible, non-transient computer storage medium.

[0063] Instrument 110 may have one or more functional modules 109. Modules 109 may operate to perform specific functions such as processing and analyzing data. Modules 109 may be implemented in hardware, software, or any suitable combination thereof. Memory 115 of instrument 110 may store computer-executable software modules that contain computerexecutable instructions. For example, one or more of modules 109 may be stored as computerexecutable code in memory 115. These modules may be read for execution by processor 111. Though, this is just an illustrative embodiment and other storage locations and execution means are possible.

[0064] Instrument 110 provides excitation signals for sensor 120 and measures the response signal from sensor 120 using impedance analyzer 117. Impedance analyzer 117 may contain a signal generator 112 for providing the excitation signal to sensor 120. Signal generator 112 may provide a suitable voltage and / or current waveform for driving sensor 120. For example, signal generator 112 may provide a sinusoidal signal at one or more selected frequencies, a pulse, a ramp, or any other suitable waveform. Signal generator 112 may provide digital or analog signals and include conversion from one mode to another. Denenberg provides a discussion of an impedance analyzer that may be used in some embodiments. See, for example, the discussion in connection with FIG. 19a which provides a discussion on how impedance analyzer 117 can take a measurement. Goldfine III provides further discussion on how such impedance measurements may be calibrated to remove certain systematic bias from the measurements.

[0065] In some embodiments, impedance analyzer 117 has a current sensor 109 that is used to measure a current leaving signal generator 112. Current sensor 109 may be any suitable sensor for measuring such current. For example, current sensor 109 may include a known series resistance in the drive current signal path and current sensor 109 may measure the voltage across such known resistance such that the current may be calculated using Ohm’s Law. As another example, current sensor 109 may measure the voltage induced on an inductive pick-up coil having a well known transimpedance.

[0066] Sense hardware 114 may comprise multiple sensing channels for processing multiple sensing element responses in parallel. As there is generally a one to one correspondence between sense elements and instrumentation channels these terms may be used interchangeably. It should be appreciated that care should be used, for example, when multiplexing is used to allow a single channel to measure multiple sense elements. For sensors with a single drive and multiple sensing elements such as the MWM®- Array eddy current array available from JENTEK® Sensors, Inc., the sensing element response may be measured simultaneously at one or multiple frequencies including simultaneous measurement of real and imaginary parts of the transimpedance (or mathematically equivalent measurements / representations such as the magnitude and phase of the transimpedance or the in-phase and quadrature components of the transimpedance). Though, other configurations may be used. For example, sense hardware 114 may comprise multiplexing hardware to facilitate serial processing of the response of multiple sensing elements and for eddy current arrays. Some embodiments of sensor 120 use certain MWM-Array formats to take advantage of the linear drive and the ability to maintain a consistent eddy current pattern across the part using such a linear drive. Sense hardware 114 may measure sensor transimpedance for one or more excitation signals at one or more sense elements 123 of sensor 120. It should be appreciated that while transimpedance (sometimes referred to simply as impedance), may be referred to as the sensor response, the way the sensor response is represented is not critical and any suitable representation may be used. In some embodiments, the output of sense hardware 114 is stored along with temporal information (e.g., a time stamp) to allow for later temporal correlation of the data, and positional data correlation to associate the sensor response with a particular location on test object 130. Instrumentation may also operate in a pulsed mode with time gates used to provide multiple sensing outputs and multiple channels used to acquire data from multiple sensing elements. If these sensing elements 123 have different drive-sense gaps (distance between a drive construct 122 and the sense elements 123, then this is referred to as a segmented field sensor. Thus, sensor operation can be at a single frequency, multiple frequencies, or in a pulsed mode where the drive is turned on and off in a prescribed manner or switched between two or more modes of excitation.

[0067] Sensor 120 is shown as an eddy-current sensor, though other sensor types may be used with system 100. For example, in some embodiments, sensor 120 is one or more of an eddy current sensor, an optical sensor, an ultrasonic testing (UT) sensor, a thermographic sensor, and a radiography sensor.

[0068] FIGs. 1B-1C show some eddy current array embodiments of sensor 120. Sensor 120 has a drive construct 122, a sense element 123 (or multiple sense elements), each of which is discussed further herein. In some embodiments sensor 120 provides temperature measurement, voltage amplitude measurement, strain sensing or other suitable sensing modalities or combination of sensing modalities. In some embodiments, sensor 120 is an eddy-current sensor such as an MWM, MWM-Rosette, or MWM-Array sensor available from JENTEK Sensors, Inc., Marlborough, MA. A discussion of some MWM-Array sensors may be found, for example, in Schlicker. Sensor 120 may be a magnetic field sensor or sensor array such as a magnetoresistive sensor (e.g., MR-MWM-Array sensor available from JENTEK Sensors, Inc.), a segmented field MWM sensor, and the like. Segmented field sensors have sensing elements at different distances from the drive winding to enable interrogation of a material to different depths at the same drive input frequency. Sensor 120 may have a single or multiple sensing and drive elements. Sensor 120 may be scanned across, mounted on, or embedded into test object 130.

[0069] In FIG. IB, sensor 120 is an eddy current array having an array of sensing elements 123 and a drive winding 121. Drive winding 121 has a single rectangular drive construct 122. Drive construct 122 has a linear segment along which sensing elements 123 are each equidistant. The distance 124, shown as the distance from the nearest linear drive segment to the center of sensor elements may be defined as a drive-sense gap. Other definitions of drive-sense gap may be found in literature or used - for example, the distance between the nearest linear drive segment and the nearest segment of the sense element coil.

[0070] In FIG. IB, sensor 120 has sensing elements 123 within the confines of rectangular drive construct 122. Sensor 120 shown in FIG. 1C is essentially identical to sensor 120 shown in FIG. IB except that sensing elements 123 outside the confines of rectangular drive construct 122. The drive-sense gap, distance 124, may be defined in the same way for both designs.

[0071] In FIG. ID, sensor 120 has a drive winding 121 where the drive construct 122 is a dual- rectangular drive construct. In some embodiments the dual rectangular drive constructs are connected such that current flows in the same direction in the two adjacent drive segments.

[0072] In some embodiments, the computer-executable software modules 109 may include a sensor data processing module that, when executed, estimates properties of test object 130. The sensor data processing module may utilize multi-dimensional precomputed databases that relate one or more frequency transimpedance measurements to properties of test object 130 to be estimated. The generation of suitable databases and the implementation of suitable multivariate inverse methods are described, for example, in Sheiretov. The sensor data processing module may take the precomputed database and sensor data and, using a multivariate inverse method, estimate material properties for the processed part or the powder. Though, the material properties may be estimated using any other analytical model, empirical model, database, lookup table, or other suitable technique or combination of techniques. User interface 113 may include devices for interacting with a user. These devices may include, by way of example and not limitation, keypad, pointing device, camera, display, touch screen, audio input and audio output.

[0073] Network interface 119 may be any suitable combination of hardware and software configured to communicate over a network. For example, network interface 119 may be implemented as a network interface driver and a network interface controller (NIC). The network interface driver may be configured to receive instructions from other components of instrument 110 to perform operations with the NIC. The NIC provides a wired and / or wireless connection to the network. The NIC is configured to generate and receive signals for communication over the network. In some embodiments, instrument 110 is distributed among a plurality of networked computing devices. Each computing device may have a network interface 119 for communicating with other computing devices forming instrument 110.

[0074] In some embodiments, multiple instruments 110 are used together as part of system 100. Such systems may communicate via their respective network interfaces. In some embodiments, some components are shared among the instruments. For example, a single computer may be used to control all instruments. In one embodiment multiple areas on the test object are scanned using multiple sensors simultaneously or in an otherwise coordinated fashion to use multiple instruments and multiple sensor arrays with multiple integrated connectors to inspect the test object surface faster or more conveniently.

[0075] Actuator 101 may be one or more actuators used to position sensor cartridge 140 with respect to test object 130 and ensure that the liftoff of the sensor 120 is in a desired range relative to the test object 130. For example, actuator 101 may drive the movement of mechanical components of scanner 150 that in turn move the sensor 120 relative to test object 130. Actuator 101 may be an electric motor, pneumatic cylinder, hydraulic cylinder, or any other suitable type or combination of types of actuators for facilitating movement of sensor cartridge 140 with respect to test object 130. Actuator 101 may be controlled by motion controller 118. Motion controller 118 may control actuator 101 to move sensor cartridge 140 and sensor 120 relative to test object 130.

[0076] Regardless of whether motion is controlled by motion controller 118 or directly by the operator, position encoder 103 and motion recorder 116 may be used to record the relative positions of sensor 120 and test object 130. This position information may be recorded with impedance measurements obtained by impedance analyzer 117 so that the impedance data may be spatially registered. For some applications the performance of system 100 depends (among other things) on the proximity of sensor 120 to test object 130; that is to say the sensor liftoff may be critical to performance for such applications. For example, crack detection in an aerospace application may require cracks 0.5 mm (0.02 inches) in length be reliably detectable in test object 130 (e.g., a turbine disk slot). In order to achieve reliable detection of a small crack, sensor 120’s liftoff may need to be kept to under 0.25 mm (0.010 inches). Further, for such an application, sensor 120 may preferably be a sensor array, thus the liftoff of each element in the array may need to be kept to under 0.25 mm (0.010 inches). (It should be appreciated that these dimensions are illustrative and the specific requirements will be dictated by the details of the application.) Measurements may be complicated when test object 130 has a complex curved surface that may change along a measurement scan path.

[0077] To permit high-performance operation at higher excitation frequencies, use of current sensor 109 to measure the current in drive winding 121 may not be sufficient. The inventors have recognized and appreciated that measurement performance may be improved by measuring the current in drive winding 121 closer to the portion of the drive conductor that is inductively coupling to sense element 123. Specifically, and as described in Dunford II, a current sense element located on sensor 120 can be used to much more accurately measure the current in drive winding 121 that is inductively coupling to sense element 123. This is contrasted with measurement of the drive current much further from sense element 123 using current sensor 109 which is typically within instrument housing 107. Although the electrical impedance of cable 180 may alter the current at the instrument, the local measurement can account for any variation of the current due to the cable.

[0078] FIG. 2 shows embodiments of instrument 110 with a specific focus on data collection and analysis. It should be appreciated that other aspects of instrument 110 discussed in connection with FIG. 1 A or elsewhere may also be part of such an embodiment.

[0079] Prior to using instrument 110 to collect and analyze sensor data as part of system 100, instrument 110 may be configured for a specific measurement application. An instrument control module 230 may be used to configure instrument 110 for a specific measurement application. Instrument control module 230 may utilize a session file 210 to store an instrument configuration 211, a measurement sequence instructions 212, and an interpolation configuration 213.

[0080] Instrument configuration 211 may store information identifying the type of sensor to be used, the excitation frequencies and their respective amplitudes, specific grids within precomputed database 203 for impedance data interpolation, the type of calibration to be used, the modules that used as part of the measurement such as the specific signatures within signature library 205 for data analysis, and other information for configuring instrument 110 for a measurement application. The calibration typically uses an air calibration or an air with a one point reference measurement calibration. For an air calibration itself, a measurement of the sensor response in air is used to adjust the measurement impedances to known and reproducible values. This approach does not require the use of reference standards for the instrument adjustment, but measurements on a reference part or material is recommended for verification of the calibration itself. To reduce channel -to-chann el variations in the sense element responses and improve consistency of the conductivity measurement, a second measurement point can be used as part of the calibration. This second measurement is usually for a reference material with known electrical properties. This provides consistency with other standard procedures for conductivity measurements. Note that one or more reference point measurements could be used but this tends to be less robust than including a measurement response in air since the reference part measurement for calibration requires knowledge of the conductivity of the reference material. The instrument configuration 211 typically also includes information about the data acquisition rate and the configuration of auxiliary information that could be associated with each measurement such as position encoder information, temperature, strain gages, etc.

[0081] Measurement sequence instructions 212 may define the sequence of actions that are to take place for a measurement. Instructions 212 may specify motor control, triggers, changes to the instrument configuration, and prompt user actions. For example, instructions 212 may indicate that after initializing a measurement, a first motor is to move at a certain speed during measurement collection and, after reaching an end point, measurement is to stop. As another example, after a first measurement is taken the instructions 212 may indicate the user is to be prompted to take an action (e.g., lay a non-conducting layer between the test object and the sensor to increase sensor liftoff) and then wait until a user initiated trigger is received. As yet another example, after taking first measurements the instructions may cause instrument 110 to be reconfigured to an alternate instrument configuration (e.g., having different excitation frequencies or other configuration properties).

[0082] Measurement sequence instructions 212 may also include definitions of the views to be presented to the end user. These views may be read by graphics generation module 270 to affect the graphical presentation to the user. Note that the graphics generation could also be in the form of data tables.

[0083] In some embodiments, an inverse interpolation module 220 is used to process impedance data 201 obtained from sensor 120 by impedance analyzer 117. Inverse interpolation module 220 utilizes a grid database 203 to estimate physical properties from impedance data 201. Physical properties estimated may include properties such as layer and gap thicknesses, electrical conductivity as a function of spatial position, and magnetic permeability as a function of spatial position. For example, the physical properties estimated by inverse interpolation module 220 for a sensor scanning a coated substrate material may include (i) liftoff, (ii) coating thickness, (iii) coating electrical conductivity, and (iv) substrate electrical conductivity. Secondary properties may also be estimated using the output of the inverse interpolation module, such as layer thicknesses, gaps between layers, the size of a chamfer, and further to estimate defect sizes or to identify types of anomalies.

[0084] Interpolation configuration 213 of session file 210 may be used to specify aspects of the inverse interpolation. For example, in some embodiments a hierarchical approach can be used to increase numerical stability and accuracy of the multiple unknown inversion. Property effects can be systematically separated from one another by using specific excitation frequencies and / or segmented fields to estimate the properties they are most sensitive to. For example, a coating conductivity property may be estimated using only a high frequency excitation measurement, and then both the high and a low frequency used to determine coating thickness and substrate conductivity (with the coating conductivity in this second step assigned the value determined from the high frequency alone). This may be useful for example for inspection through a bushing. In one embodiment of this invention, the use of multiple frequencies and the inverse interpolation module along with the ability to scan the internal surface of the busing in a hole, is used to detect cracks in the stackup / layers / skins through a bushing. This can utilize other aspects of this invention, after accounting for the thickness and properties of the busing to estimate the conductivity or magnetic permeability of the “substrate” which in this case is the properties of the structural layers, aircraft skin, material that is inspected through the busing.

[0085] Further discussion of the operation of inverse interpolation module 220 may be found in Sheiretov.

[0086] In some embodiments, instrument 110 is also equipped with a forward model module 240 for precomputing grids for grid database 203 using a sensor-material model. The model may be a physics-based model, an empirical model based on prior measurements, or any other suitable type of model for creating measurement grids. In some embodiments, forward model module 240 is not made a part of instrument 110 and only grids are stored in grid database 203 of instrument 110. For example, forward model module 240 may be a software application run on a computer to produce grids which are then stored in grid database 203. In some embodiments, instrument 110 includes a signature definition module 250 for defining characteristic responses (“signatures”) of a feature to be enhanced or suppressed in measurement data. Signature definition module 250 may allow a user to identify signatures and store them in a signature library; alternatively or additionally, signatures may be identified in an automated or semi-automated way. For example, a crack defect signature may appear in the electrical conductivity response measured by a sensor scanning over the crack. In the case of a sensor array, the response may be observed on a single or multiple adjacent channels. A signature may be identified as a single channel response or a multi-channel response. Signature definition module 250 may standardize signatures prior to storing them in library 205. For example, signatures may be standardized to a specific number of points or a specific amplitude range. Signatures may also include metadata that provide additional information about the signature such as the size of the defect the signature was obtained from.

[0087] Detection and sizing module 260 may be used to detect and size defects in measurement data from a test object using signatures from signature library 205. Module 260 may evaluate the correlation between a measurement and a signature. If the correlation exceeds a threshold a detection may be flagged. The threshold may be set based on the detection and false alarm requirements of the application. Signature library 205 may contain multiple signatures that may be tested against measurement data. The signature having the greatest similarity with the measurement may also be used to size a detected defect. For example, the defect size may be estimated to be the same as the size of the defect the signature.

[0088] Module 260 may also be used to suppress features that are not of interest such as fasteners or through holes. For example, a through hole in a plate typically has a significant effect on the estimated electrical conductivity of the substrate material if a planar model is used to estimate conductivity. The shape of the conductivity response with respect to position as the sensor is scanned over the hole depends upon the actual electrical conductivity of the substrate material, the excitation frequency, and the geometry (e.g., sense element size and spatial wavelength) of the sensor. However, for a given sensor array, because the conductivity response of the through hole is consistent, it may be removed from the conductivity estimate. For example, module 260 may identify a highly correlated through hole signature with the conductivity response from measurement. The conductivity response may then be updated to remove the signature. This will flatten the conductivity response and may also allow for the hole location to be accurately estimated from the measurement data. While this example discussed suppressing the response for processed data such as the estimated conductivity of the material this approach can also be used for unprocessed data such as the sensor impedance or transinductance.

[0089] Graphics generation module 270 may provide a graphical representation to the user to assist the user in the data collection and / or analysis process. Module 270 may present such a graphical presentation on a video display integral to and / or separate from instrument 110. Information may be presented as tables, A-scans, B-scans, C-scans, or any suitable way. In some embodiments, module 270 configures the graphical environment based on instructions 212. In this way a consistent presentation of information can be provided to the user.

[0090] Report Generation Module 280 may be included to facilitate review of measurement results outside of the graphical environment of instrument 110. For example, report generation module 280 may produce a report of measurement data in pdf, docx, rtf, xlsx, or other suitable format. Session file 210 may specify the report format which may be used by module 280 to generate reports for measurement data.

[0091] In some embodiments, the output includes a decision with regards to the future disposition of the test object. Modules 270 and / or 280 may present such a decision. Examples include pass / fail decisions on the quality of a component, or the presence of flaws. As another example, it may be determined whether the test object may be returned to service, repaired, replaced, scheduled for more or less frequent inspection, and the like. If it is determined that the application was not determinative, instrument 110 may re-perform the procedure(if automated), or advise the user to re-perform the procedure. A procedure may need to be re-performed, for example, if all requirements of the procedure were not met. For example, the procedure may require the liftoff of the sensor to be below a threshold amount over the inspection surface and require re-performance if the liftoff requirement is not met.

[0092] Software implementations are focused on increasing data analysis, speed and large file handling. In one such embodiment, software is upgraded from 32 bit to 64 bit to improve the speed of data analysis and rendering of multiple images for viewing analyzed data. In some embodiments, multithreading, vector processing, or other methods for implementing rapid data analysis for multivariate inverse methods, intelligent filtering, or AI / ML implementations are utilized to improve the speed for data analysis and viewing. Inspection speed may also be affected by the scan speed of motors and the data acquisition rate. The scan speed of motors and data acquisition rate are set to provide a minimum number of data points on a prescribed defect size (e.g., 50x50 mil comer cracks, or 50x25 mil midwall cracks) where the minimum number of data points required is determined from empirical data taken at two or more scan speeds / data rate combinations. Scan speeds and data rate should also take into account the type of data analysis to be implemented (e.g., MIM, intelligent filtering, AI / ML). Intelligent filtering is the use of signature libraries and shape filtering as described, for example, in Dunford I.

[0093] In some embodiments the measurement results are used to control a process. For example, a property measurement may be fed back into a control circuit that controls a process.

[0094] Attention is now turned to FIG. 3 A which shows a system 310 for hole inspection according to some embodiments. System 310 may be used, for example, to inspect holes in aerospace and other application fields to determine if the hole has fatigue cracks or other forms of damage. System 310 may generally be considered an embodiment of system 100, and thus the discussion of system 100 is generally applicable to system 310. System 310 may include an instrument 110 such as that described with reference to FIG. 1 A, a handheld scanner 300, and a sensor cartridge 140.

[0095] FIG. 3B shows an example test object 130 having layers 131-A, 131-B, and 131-C, generally referred to as layers 131. Test object 130 may have any number of layers 131 and the illustration of three layers is for example only. Test object 130 has a hole 132 to be inspected. In some discussions the term “stackup” is used to refer to the sequence of layers in a test object 130.

[0096] Cable 180 is shown in FIGS. 3D through 3F. This cable carries power, data, and communication signals between instrument

[0097] Scanner 300 is a device for changing the position of sensor cartridge 140 relative to hole 132 and facilitating inspection measurements of the hole by instrument 110. Scanner 300 may be connected to instrument 110 by a cable 310 such that instrument 110 can be, for example, a few feet away from scanner 300. Though, instrument 110 may interface with scanner 210 and sensor cartridge 140 in any suitable way. In some embodiments, scanner 300 and instrument 110 are an integrated assembly.

[0098] Scanner 300 may control both the axial and circumferential position of sensor 120 within hole 132, though in some embodiments sensor 120 may be an array of sufficient size such that scanning in only one direction is necessary. For example, sensor 120 may be a sensing array that provides coverage around the entire circumference of hole 132 such that scanning may only need to be performed in the axial direction. As another example, sensor 120 may be a sensor array that provides coverage along the entire depth of the hole such that scanner 210 may only need to scan in the circumferential direction. In some other embodiments, sensor 120 only provides partial coverage in both the axial and circumferential directions and scanner 300 may control motion in both directions to facilitate inspection of the hole. Scanner 300 may include circumferential actuator 301, circumferential position encoder 303, axial actuator 302, axial position encoder 304, trigger 305, and motion controller 306. Scanner 300 also includes hardware for mechanically supporting sensor cartridge 140.

[0099] Circumferential actuator 301 may be used to control the circumferential position of sensor 120 relative to hole 132. Similarly, axial actuator 302 may be used to control the axial position of sensor 120 relative to hole 132. Any suitable actuator may be used such as an electric motor. In some embodiments the axial and / or the circumferential position may be controlled by hand or using a mechanical device without use of automation.

[0100] Circumferential position encoder 303 and axial position encoder 304 record the position of sensor 120 in the circumferential and axial directions, respectively. In some embodiments, the circumferential and / or axial position encoders may not be required.

[0101] Trigger 305 provides a mechanism for user input to control the scanning and inspection process. Trigger 305 may be, for example, one or more physical buttons or momentary switches. Though trigger 305 may generally be any suitable form of user input such as those described in connection with user interface 113 (FIG. 1 A).

[0102] FIG. 3C shows an embodiment of system 310 having a handheld instrument 400, scanner 300, and an external flex-cable 320, each of which is discussed further herein.

[0103] FIG. 3D shows a detailed view of an embodiment of motion controller 306 of scanner 300. In the illustrated embodiment, motion controller 306 includes an inner board 330 and an outer board 340. The inner board 330 includes a stepper motor driver 331, DC motor driver 332, a power supply 334, an incremental encoder 335, and a line driver 333. The outer board 340 includes a microcontroller 341 and a second stepper motor driver 342. The motion controller may be adapted to utilize various types of actuators, such as DC motors, servo motors, or linear actuators, in conjunction with appropriate motor drivers to achieve the desired mechanical function. Further information is also illustrated in Section III - Hole Scanner.

[0104] In some embodiments, the stepper motor driver 331 provides suitable control of bipolar stepper motors using PWM microstepping control allowing for smooth and accurate stepper motor tuning, stall detection, and current regulation. Stepper motor driver 331 is connected via connectors 350 to handheld scanner 300.

[0105] According to some embodiments, the DC motor driver 332 provides support for N- channel H-bridge motor control, current sensing and regulation, and protection circuitry. DC motor driver 332 is connected via connectors 350 to handheld scanner 300.

[0106] According to some embodiments, the power supply 334 is used for continuous voltage regulation and power delivery to the line driver 333, incremental encoder 335, and to the outer board 340 via connectors 350. The power supply 334 is used to satisfy voltage and current requirements and maintain stable output voltages at different load conditions.

[0107] In some embodiments, the incremental encoder 335 supports motion sensing and positioning feedback. Incremental encoder 335 is a reflective encoder that detects accurate motor positioning. Incremental encoder 335 output is connected to line driver 333.

[0108] According to some embodiments, the line driver 333 is a quad differential line driver supporting RS-485 / RS-422 communication standard. Line driver 333 output is connected to handheld scanner 300 via connectors 350.

[0109] In some embodiments, a microcontroller 341 serves as the primary channel of read / send data, and control of stepper motor driver 342, stepper motor driver 331, and DC motor driver 332. Microcontroller 341 is connected to inner board 330 via connectors 350.

[0110] In some embodiments, stepper motor driver 342 provides suitable control of bipolar stepper motors using PWM microstepping control allowing for smooth and accurate stepper motor tuning, stall detection, and current regulation. Stepper motor driver 342 is connected via connectors 350 to Handheld Scanner 300.

[0111] Section II - Impedance Instrumentation

[0112] FIGs. 1 A and 2 above, describe instrument 110 according to some embodiments. This section provides additional and alternative embodiments of instrument 110. The embodiments described may have the same or similar features as those described in connection with instrument 110.

[0113] FIGs. 5A-5H shows views of handheld instrument 400, according to some embodiments.

[0114] FIG. 5 A shows a front perspective view of handheld instrument 400, according to some embodiments. Visible features of instrument 400 are a protective boot 401, an integrated display 413, sensor / cable connector 424, and mounting points 402.

[0115] FIG. 5B shows a rear perspective view of handheld instrument 400, according to some embodiments. Visible features of handheld instrument 400 include a kickstand / handle 403, sealed connectors 420, including a power port for charging and power 421, I / O port 423, and a power button 422. Features may include, in some embodiments, a heatsink 405, fan 404, curved channels / ducts / for fan 406, inclined bumpers on back 407, batteries housing 475, and a kickstand / handle 403. Heatsink 405 design includes heat conduction through the sealed housing 470 and features external enhancements, such as integrated heatsink 405 fins. In some embodiments, sealed housing 470 can operate with or without fan 404. Inclined bumpers on back 407 ensure that the handheld instrument 400 remains vertically to heatsink 405 when resting on a flat surface. Curved channels / ducts / for fan 406 direct the airflow to the locations expected to reach the highest temperature. Fan 404 is located outside the sealed housing 470. Fan 404 may have suitable ingress protection to match the housing. Sealed housing 470 is ingress protect! on(IP) rated, and provides a barrier that prevents the entry of particles and other contaminants.

[0116] FIG. 5C shows a plan view of the right side of handheld instrument 400, according to some embodiments. FIG. 5D shows a plan view of the front side of handheld instrument 400, according to some embodiments. FIG. 5E shows a plan view of the left side e of handheld instrument 400, according to some embodiments. FIG. 5F shows a plan view of the top side of handheld instrument 400, according to some embodiments. FIG. 5G shows a plan view of the back side of handheld instrument 400, according to some embodiments. FIG. 5H shows a plan view of the bottom side of handheld instrument 400, according to some embodiments. FIG. 51 shows a bottom view and the internal parts of handheld instrument 400, according to some embodiments. Features may include a sealed housing 470 (ingress protection).

[0117] FIG. 5 J shows the internal parts of handheld instrument 400, according to some embodiments. Features may include a computer 410, electronics boards for impedance analyzer 417, and shielding 480 between instrumentation boards and computer board 410.

[0118] FIG. 5K shows the internal parts of handheld instrument 400, according to some embodiments. Features may include an auxiliary board 440 and a display interface board 414.

[0119] FIG. 6 shows another handheld instrument 500 according to some embodiments. In some embodiments, the handheld instrument 500 has a similar form factor as the instrument in FIGs. 6A-6O of Goldfine IV,.

[0120] FIG. 6A shows a block diagram of handheld instrument 400, according to some embodiments.

[0121] In some embodiments, a sealed housing 470 is ingress protection (IP) rated, and provides a barrier that prevents the entry of particles and other contaminants.

[0122] Handheld instrument 400 includes an impedance analyzer 417. Impedance analyzer 417 may be implemented via one or more electronics boards in ways similar to those described in Goldfine IV. In some embodiments, the electronics boards used to form impedance analyzer 417 are usable in multiple form factors. For example, they may be usable in both handheld instrument 400 and in handheld instrument 500, described below. Impedance analyzer 417 may be similar to impedance analyzer 117 (e.g., FIG. 1A). Impedance analyzer 417 is discussed further below in connection with handheld instrument 400.

[0123] Handheld instrument 400 may include a computer 410. Computer 410 may have a commercially available form factor and sealed housing 470 may be adapted to support such form factor such as a Next Unit of Compute (NUC). Though any suitable computer may be used. Computer 410 may provide a processor 411 (e.g., similar to processor 111), memory 415 (e.g., similar to memory 115), network interface 418 (e.g, similar to network interface 119), and other sealed connectors components.

[0124] Handheld instrument 400 may include an integrated display 413 and a display interface board 414. The display interface board 414 provides all functions related to the integrated display 413, including a thin-film-transistor (TFT) display, a projected capacitive touch panel, brightness level control, and power delivery. Integrated display 413 may be connected via the display interface board 414 and controlled by computer 410.

[0125] Handheld instrument 400 may include batteries 430. Batteries 430 are discussed further below in connection with auxiliary board 440. Batteries may be hot swappable and may also be rechargeable inside or outside of the instrument.

[0126] Handheld instrument 400 may include an auxiliary board 440 for managing various functions of instrument 400. Auxiliary board 440 is discussed further in connection with FIG. 6B.

[0127] Handheld instrument 400 may include an instrument cable 320 for connecting to handheld scanner 300. Instrument cable 320 may be made similar to cable 180 (e.g., discussed in connection with FIGs. 4A-4D). Though, cable 320 may be made in any suitable way.

[0128] Handheld instrument 400 may include sealed connectors 420, including a power port for charging and power 421, an VO port 423, and a power button 422. These sealed connectors 420 are ingress protection (IP) rated, preventing particles and other contaminants from entering the sealed housing 470. The power port for charging and power 421 serves as the primary power input, providing a secure connection for delivering external power to handheld instrument 400. The I / O port 423 serves as the primary communication input to computer 410. Power button 422 enables and disables power to handheld instrument 400.

[0129] FIG. 6B shows a detailed view of the auxiliary board 440. Auxiliary board 440 includes a power management module 450 and a communication module 460. In some embodiments, the modules of auxiliary board 440 are integrated onto a single printed circuit board (PCB), though other suitable configurations may be implemented. The auxiliary board 440 board design is also modified to locate regions likely to experience high temperatures in a manner suitable for conduction of heat to a convenient location where it can be dissipated via heat sink 405 and fan 404 can provide efficient convective cooling.

[0130] The power management module 450 is responsible for managing batteries 430 and receiving power from an AC adapter 444, battery charge control 451, power selection 452, and power supply output 360 to peripheral hardware 442 and board electronics 443 (e.g., sensors and microcontroller). The power management module 450 is illustrated by the block diagram in FIG.6B.

[0131] In some embodiments, an AC adapter 444 provides a suitable input voltage, supplying power to the auxiliary board 440. The AC adapter 444 delivers stable direct current (DC) voltage to the auxiliary board 440, including board electronics 443 and peripheral hardware 442. AC adapter 444 serves as the primary power source for charging batteries 430. An AC adapter 444 (not shown) may be integral to handheld instrument 400 or external to handheld instrument 400. The AC adapter 444 may have sealed connectors 420. Sealed connectors 420 may be integral to handheld instrument 400.

[0132] According to some embodiments, batteries 430 serve as the secondary input voltage source for the auxiliary board 440, including board electronics 443 and peripheral hardware 442. Batteries 430 are selected to meet the specified power requirements of the handheld instrument 400. Batteries 430 includes safety features such as protection against over-charge, overdischarge, over-drain, and short circuit. Two batteries 430 may be either hot-swappable or simultaneously connected to the auxiliary board 440 through connectors 441.

[0133] According to some embodiments, connectors 441 are responsible for power delivery from batteries 430 and AC adapter 444 to board electronics 443, including the power management module 450 and communication module 460, and peripheral hardware 442, including computer 410, integrated display 413, and the impedance analyzer 417.

[0134] According to some embodiments, the battery charge control 451 is optimized for Lithium-Ion (Li-Ion) batteries 430 and handles various aspects of power management, including power switching, voltage regulation, charge preconditioning, AC adapter 444 regulation, and charge status monitoring. Key characteristics and functions include a synchronous switched- mode buck converter which reduces the power dissipation increasing efficiency, preconditioning mode to bring completely discharged batteries 430 to an acceptable operational level, and capacity monitoring to prevent batteries 430 overcharging.

[0135] According to some embodiments, the power selection 452 is an automatic PowerPath switchover integrated circuit (IC), that is used to switch between batteries 430 and / or AC adapter 444. The power selection 452 is specifically configured for Load Sharing Operation, a mode utilized when input voltages are relatively the same. The power selection 452 determines the most appropriate power source, including batteries 430 or / and AC adapter 444, by comparing the input voltage rail while avoiding any interruptions in power delivery in the power supply output 360. The power selection 452 also prevents overcurrent and reverse current conditions that may arise during power delivery in the power supply output 360.

[0136] In some embodiments, the power supply output 360 is used for continuous voltage regulation, and power delivery to board electronics 443, and peripheral hardware 442, including computer 410, integrated display 413, and the impedance analyzer 417, ensuring consistent and reliable hardware operation. The power supply output 360 is used to satisfy voltage and current requirements of analog and digital circuits, optimize power efficiency, and maintain stable output voltages at different load conditions.

[0137] The communication module 460 provides a communication channel between computer 410 and microcontroller 463 which may be used to control various features of handheld instrument 400. In some embodiments, the communication module 460 utilizes a Universal Asynchronous Receiver-Transmitter (UART) communication bus 462 over a USB-to-Serial UART interface 461 between the computer 410 and microcontroller 463. Though this is exemplary and other communications protocols may be used. An Inter-Integrated Circuit (I2C) communication bus 464 is used as a secondary communication protocol to read and receive data from / to board electronics 443 (e.g. fuel gauge and temperature sensors). A General Purpose Input / Output (GPIO) interface control 465 is used by the microcontroller 463 to control board electronics 443 and peripheral hardware 442. The communication module 460 is illustrated by the block diagram in FIG. 6B.

[0138] According to some embodiments, the USB-to-Serial UART interface 461 serves as the primary channel of communication between the computer 410 and the microcontroller 463. The USB-to-Serial UART interface 461 is responsible for asynchronous serial data interface and handling of USB protocol. The USB-to-Serial UART interface 461 is connected via connectors 441 to the computer 410.

[0139] In some embodiments, the UART communication bus 462 utilizes American Standard Code for Information Interchange (ASCII) characters that are sent from the computer 410 and received by the microcontroller 463 via the UART communication bus 462, enabling the computer 410 to send commands to adjust the integrated display 413 screen brightness, enable / disable the power switch ! 323 of the impedance analyzer 417, read status / feedback indicator lights from board electronics 443, and gather temperature and charge capacity data from batteries 430.

[0140] In some embodiments, the microcontroller 463 serves as the primary channel of read and send data, and control of board electronics 443 and peripheral hardware 442. In some embodiments, an I2C communication bus 464 is nested under the UART communication bus 462. 12C is used as a master / slave communication for reading the temperature (i.e., obtained from board NTC thermistors) and estimating available fuel gauge capacity from the batteries 430. Data from the microcontroller 463 is exchanged and transmitted via the I2C communication bus 464, namely the Serial Data Line (SDA) and Serial Clock Line (SCL).

[0141] According to some embodiments, the GPIO interface control 465 is responsible for the control of board electronics 443, including the status / feedback of light emitting diodes, power switching of of the impedance analyzer 417 via a metal -oxide-semiconductor field-effect transistor (MOSFET), and adjust of screen brightness of integrated display 413 via pulse-width modulation (PWM).

[0142] Handheld instrument 500 may utilize the same electronics boards to implement impedance analyzer 417 as discussed in connection with instrument 400. In some embodiments, impedance analyzer 417 provides a power pass through; that is, power can pass through instrument 417 from [input port] to sensor / cable connector 424. Here the term “power” is used to refer specifically to a DC voltage source such that a device connected via sensor / cable connector 424 may be powered “through” instrument 500 (e.g., to a motorized scanner via external flex cable).

[0143] In some embodiments of impedance analyzer 417, the drive measurement channel can be switched between utilizing a remote current sense element and one or more internal current sense options (e.g., resistive current sense, one or more inductors internal to instrument 300 of the same or different inductances). Remote current senses may be similar to those described in Dunford II.

[0144] In some embodiments of impedance analyzer 417, temperature sensors are provided to monitor the temperature of high power or heat sensitive components such as analog to digital converters (ADC), field programmable gate array (FPGA), and the driver circuit (electronics that provide the electrical current for the sensor’s drive winding).

[0145] Power / data connector provides power and data connectivity for instrument 500. Data may be exchanged with an outboard computer. In some embodiments, a power / data connector is more robust than a standard Ethernet connector (RJ45). For example, power / data connector may provide improved durability and ingress protection for the instrument housing compared to a standard Ethernet connector. If data connectivity is achieved through an outboard computer’s Ethernet port, Ethernet magnetics (isolation transformers) may be included on the corresponding electronics board of impedance analyzer 417. (Isolation transformers are normally part of a standard Ethernet connector’s hardware.)

[0146] In some embodiments, impedance analyzer 417 includes an inductive current sensor for inductively measuring the current flowing through drive connector. In some embodiments, the inductive current sensor utilizes rectangular elements. The rectangular element design may reduce electromagnetic interference in the measurement and provides a more predictable inductance since the design has lower sensitivity to nearby materials than a circular design. In some embodiments, impedance analyzer 417 features a resistive current sensor.

[0147] Section III - Hole Scanner

[0148] This section describes various embodiments of a hole scanner 300, seen in FIGs. 8A-8J that may be used, for example, as part of system 100 or system 310 (e.g., handheld scanner 300, FIG. 3) as well as flex cable 320 for connecting handheld scanner 300 to impedance analyzer 117 for high quality and convenient measurement. In some embodiments, handheld scanner 300 is sealed from outside elements for data acquisition in harsh environments.

[0149] Handheld scanner 300 performs automatic scanning of hole 132 with sensor 120 in a compact handheld package small enough to easily fit in the palm of an average female hand. In some embodiments handheld scanner 300 includes three actuators to perform automation functions; circumferential actuator 601 may rotate sensor 120 through geartrain 640 seen in FIGs 10B, 15, and 16, axial actuator 602 draws sensor 120 in and out of hole 132 in some embodiments using a leadscrew 616, and mandrel actuator (solenoid) 603 locks the rotation of the Mandrel Torque Nut 711 to allow contraction of mandrel 700 for moving in and out of hole 132 without friction. Scanner 300 is designed to be operated with either the right or left hand.

[0150] Scanner internal cable 608, in some embodiments, is a FPC (flexible printed circuit) that carries the signals from instrument cable 320 to sensor 120; provides power to motion control electronics 609; carries encoder and trigger signals to instrument 110; supports I2C communication between scanner 400, sensor 120, and instrument 110; relays user inputs from triggers 607; and carries the signals of upper limit switch 610, lower limit switch 636, and sensor limit switch 637 to provide automation feedback.

[0151] Scanner internal cable 608 may include several features to maintain sensor signal integrity between sensor 120 and instrument 110. The drive conductors and power conductors may be physically separated from the sensing element leads to minimize cross coupling. The sensor leads may include flux cancellation leads either parallel (same plane) or co-linear (two layer). In addition, a dedicated current sense channel may be supported by this cable. This cable may include a protective coating that is flexible enough to enable inspection for the features of interest and durable enough to prevent kinking, impact damage, tearing and other such failure or damage modes. In addition, the connector to the instrument cable 320 may be positioned to minimize interference with the operator of the scanner using a single hand operation

[0152] Sensor 120 may be installed into mandrel cartridge 700. Mandrel cartridge 700 can be quickly changed for unique inspection purposes and for replacement in the case of wear and tear. In some embodiments, mandrel cartridge 700 includes lower nut 710 and upper nut 711 which may be fixed or rotated with a socket. Lower nut 710 is used to rotate mandrel cartridge 700 in scanner 300. The upper nut 711 may be used to resist rotation by fixing it with a socket, which allows the mandrel body helical elements 704 to be contracted by imposing a torque via rotating the lower nut. Importantly, mandrel cartridge 700 retains the wrapping lead portion of sensor 120, simplifying mandrel cartridge 700 changes and replacements and protecting sensor 120.

[0153] Mandrel cartridge 700 may be installed by plugging into shuttle assembly 670 (FIGs. 9A-9D) in scanner 300 which houses the sensor connector 661 on the internal cable 608. In some embodiments, scanner 300 is designed with sensor 120 positioned in the 'nose' of scanner 300, which is the narrowest part of the scanner 300. This configuration allows sensor 120 to be positioned as close to the edge of scanner 300 as possible, enabling inspection in tight or nearcorner areas. The placement in the nose is intentional, ensuring optimal access for inspecting regions that are otherwise difficult to reach, such as comers or confined spaces. The shuttle assembly 670 moves up and down in scanner 300 by axial actuator 602 which, in some embodiments, is a lead screw 616 driven by an electric motor. The shuttle may include numerous features to provide necessary functions and allow convenient cartridge changes as described below.

[0154] Mandrel 700 may only be installed when the shuttle is in the bottom position. Pivoting door 611 can be opened or closed by the user to provide access to cartridge cavity 612 for cartridge changes. Pivoting door 611 prevents anything from being in the path of the shuttle and impeding movement or otherwise disturbing the sensor connection, while also removing opportunity for user pinch points.

[0155] Shown in FIGs. 9A-9D, 10A-C, 11, and 12A-12C, shuttle assembly 670 allows connection with sensor mandrel 700 and consists of shuttle upper body 613 and shuttle lower body 614, which are held together with shuttle assembly retention mechanism 634. In some embodiments, this may be two springs on shoulder screws. Shuttle upper body 613 and shuttle lower body 614 move up and down together on guide on handheld scanner 300, which in some embodiments may be holes or linear rod guide 633 riding along linear rods 615. In embodiments with a lead screw actuator, lead screw 616 may pass through the shuttle upper body 613 in lead screw passage 635 and draws the shuttle lower body 614 up and down while the shuttle upper body 613 is forced against the shuttle lower body 614 with shuttle assembly retention mechanism 634. In some embodiments, shuttle assembly 670 may include features to transmit rotation to the sensor from circumferential actuator 601. In some embodiments, the two shuttle bodies retain two gears, drive gear 617 and idler gear 618. Drive gear 617 is engaged with drive nut 710 on sensor mandrel 700 when installed and rotates sensor mandrel 700 during scans. Importantly, idler gear 617 transmits power from the long gear 619 to drive gear 617 to allow for a smaller diameter of the drive gear. This is to reduce the radius of the scanner ‘nose’ to allow scanning of holes in comers and other challenging geometry. Also retained between the two bodies and below the two gears is a lifter tab 629. This Lifter Tab is inline with a Drive Disengage Tab 630. When the shuttle is in the bottom position, the user can slide the Drive Disengage Tab upwards in its slot, lifting the Lifter Tab, Drive Gear, Idler Gear, and Upper Shuttle Body. The Drive Gear needs to be lifted out of the way of the Mandrel Cartridge Drive Nut and Torque Nut to install or uninstall Sensor Mandrel Cartridges. Once the drive is disengaged, the sensor mandrel can be plugged into the scanner. When the user releases the Drive Disengage Tab, the shuttle retention mechanism 634 returns the upper shuttle and associated components to the lower shuttle and engages the drive gear 617 with the mandrel lower nut 710. To remove or replace a mandrel, the shuttle is moved to the bottom of the scanner, the door is opened, the drive is disengaged, and the user unplugs or ejects the sensor mandrel.

[0156] Scanner 300 may also include mandrel actuator 603 to contract the sensor mandrel. In some embodiments, mandrel actuator 603 is a latching solenoid installed into the upper shuttle body and includes an antirotation mechanism 638. In some embodiments, antirotation mechanism 638 may be a solenoid armature with a socket and off-center positioning of the mandrel and armature axis. The Drive Gear 617 is tall and includes a bore 651 to house antirotation mechanism 638. During scans when the rotational actuator is rotating the sensor and acquiring data, the antirotation mechanism is disengaged with the Torque Nut 711, allowing the Mandrel to rotate with the Drive Gear. When engaged, the antirotation mechanism locks the torque nut. When the torque nut is locked and the mandrel is rotated, a torque is imposed on the mandrel helical elements 704, causing them to contract. This reduces the diameter of the sensor mandrel allowing the sensor mandrel to be inserted into, removed from, and move in and out of the hole without friction.

[0157] Scanner 300 may include limit switches to provide additional feedback to the shuttle and sensor positions as seen in FIGs. 14A and 14B. In some embodiments, three limit switches are included on internal flex cable 608, one end of which is installed on the shuttle: Upper Limit Switch 610, Lower Limit Switch 636, and Sensor Rotation Limit Switch 637. Two of the limit switches detect the upper and lower positions, and the 3rd limit switch detects when the sensor is fully wrapped in the mandrel. The Sensor Lead Limit Switch may include a Button which sticks up from the sensor plug and protrudes into an opening in the Mandrel Cartridge 721. As the wrapping lead runs out of slack, the tightening of the lead displaces this switch, providing feedback to stop from overrotating the mandrel.

[0158] In some embodiments the scanner includes a geartrain to transmit motion from actuator 601 to sensor 120. In some embodiments, Idler Gear 618 is continuously engaged with the Long Gear 619 as the Shuttle Assembly is moved up and down. This allows the rotation actuator 601 to rotate the mandrel at any axial position as the mandrel is moved up and down in the hole. The Long Gear is on a gearshaft 632 with a reduction gear 620. This gear is engaged with the smaller gear of a compound gear 621. The Motor Gear turns the larger gear of the compound gear 622. This describes one embodiment of the geartrain, which allows the use of low-cost and compact motors.

[0159] The scanner may include encoders to provide detailed position feedback. In some embodiments, a reflective codestrip 605 is included on the shuttle assembly which provides linear encoding. This codestrip is read by a fixed optical encoder mounted directly to the motion control electronics 609. In some embodiments, a rotary encoder 603 is installed on the gear train. Gears may be installed on a gearshaft 631 which extends near the top of the scanner where a rotary encoder is installed.

[0160] In some embodiments, Scanner 300 components such as the Shuttle Assembly, Rotation Motor, Rotational Encoder, and Geartrain are housed in the Scanner Chassis 624. In some embodiments, a Bottom Plate 625 installs to the bottom of the Scanner Chassis and retains the gear shafts and Drive Disengage Tab. In some embodiments, scanner 300 includes an Upper Chassis 660 as shown in FIGS. 13 A and 13B which houses the axial actuator 602 which may be an Axial Motor and Lead Screw 616, handle mounting block, and mounting locations for Cable Connector 628 and trigger 607. The axial actuator 602 may be motor and lead screw 616.

[0161] In some embodiments the internal flex cable 608 wraps over the Upper Chassis and is connected to the Motion Control PCBs. The Scanner Cap 627 is installed over the Upper Chassis and covers the FPC, Motion Control PCBs and retains the trigger caps for the user input buttons. In some embodiments, the cable connector 628 protrudes from the scanner cap and provides mechanical retention of the instrument cable 320. The trigger(s) may be conveniently located on the scanner such that a finger or thumb can be used without repositioning to start a scan. Control for the scanner actuators may be provided by a remote computer or by onboard motion control electronics 609. In some embodiments these electronics may include one or more PCBs. Sensor motion and scanner operation is highly controlled in synchrony with the scan plan to acquire sensor data as desired in the hole.

[0162] Section IV - Mandrel

[0163] The sensor cartridge 140 may be a sensor mandrel such as described in Dunford I and as shown by the sensor mandrel cartridge shown in FIGS. 17A through 17C. The sensor mandrel cartridge may include a sensor 120, a mandrel body 701, and a mandrel case 702. As before, the sensor 120 is mounted to a helical element 704, the sensor lead 707 wraps around the spindle 703, and the helical element(s) 704 of the mandrel body 701 can be rotated and contracted via applied torque between lower nut 710 and upper nut 711 as shown in FIG. 18. Helical element(s) 704 may be of several profiles and in several pluralities, some examples are shown in FIGS. 20A through 20D..

[0164] In some embodiments, the Sensor Wrapping Lead 707 and Sensor Connector 706 are retained in the Mandrel Case 702. The Mandrel Body can rotate freely in the Mandrel Case until the Wrapping Lead runs out of slack. As shown in FIG 19., the sensor lead may wind tight or unwind in the case cylinder volume for wrapped lead 705. This enables a compact self-contained cartridge with a connector 706 to the internal scanner cable 608 without the operator needing to handle the sensor lead and avoiding damage and installation challenges. The scanner and cartridge design also allows for reduced length of sensor leads. The Mandrel Case may include limit switch opening 721 for sensor rotation limit switch 637 when the Mandrel Cartridge is installed into Scanner 300. When the Wrapping Lead begins to tighten, it makes contact — either directly or through an intermediate component — with the Sensor Limit Switch 637, allowing this condition to be detected. In some embodiments, the Wrapping Lead itself contacts the switch, while in others, a Limit Tape, which has slightly less slack than the Wrapping Lead, makes contact with the Limit Switch first. Other variations and embodiments are also possible.

[0165] The Mandrel Body may include 0, 1, 2, 3 or more helical elements, depending on the hole diameter and sensor size, or other sensing requirements. Sensors Mandrels with fixed diameter and a generally cylindrical or spherical body without helical elements are also supported.

[0166] In some embodiments, Mandrel Case 702 is a clamshell design with two halves and a living hinge and is molded or printed from 1 piece in the open condition for installation. One half includes retaining clips, and the other half includes latches. Once the Sensor is installed onto the Mandrel Body, the Mandrel Body is inserted into the Mandrel Case, and the Case is closed and latched around the Mandrel Body and Sensor Connector. The case is a semi -permanent install and is never opened during the life of the Mandrel Cartridge. The Mandrel Case can be opened to recycle the Mandrel Body and Case into a refurbished Mandrel Cartridge with a new Sensor. Other case types such as permanently molded or removable and user serviceable are also supported.

[0167] Section V - Hole Inspection Procedures

[0168] This section includes a description of some embodiments of the procedures that may be used to inspect holes. The scanning system discussed, for example, in the above sections, may be used, though the methods may be applicable to other systems as well.

[0169] FIG. 21 is a flow diagram of a method 800 which is used in some embodiments for inspecting holes. Steps 801 through 805 comprise Scan 1, a first complete scan of the hole. At step 801 the scanner is positioned at its initial axial position at the top of the hole. In some embodiments the proper initial axial position of the scanner is determined by performing a scan while plunging axially into the hole. A transition from air to metal is found by monitoring the electrical conductivity and lift-off measurements as the plunge proceeds. In some embodiments, this plunge scan is also used to determine the layer configuration of the hole, including layer thicknesses and material type and the location of the bottom of the hole. In other embodiments, a low resolution spiral scan is used for this purpose which may not provide complete coverage but in which at least one sensing element covers every axial position over the course of the scan. At step 802 a complete circumferential scan is performed at the initial axial position. At step 803 the axial position is incremented one-half sensing element width (times 0.707 if using a 45- degree sensor orientation) and a complete circumferential scan is performed. At step 804 the axial position is incremented by the full width of the sensor array minus an overlap and a complete circumferential scan is performed. For example, in some embodiments the overlap used may be such that the axial increment is 80% of the sensor array width. In some embodiments the axial increment at this step is not always fixed but rather is adjusted in order that at each edge of each layer, a circumferential scan is performed such that the center of one sensing element is aligned with the top edge of the layer and another is performed such that the center of one sensing element is aligned with the bottom edge. By always being positioned the same with respect to the layer edges this approach can reduce the number of signatures that are required to process the data for defect detection. At step 805, if the bottom edge of the hole has not yet been found then steps 803 and 804 are repeated, otherwise the method proceeds to step 806. After each circumferential scan in steps 802, 803, and 804, the scan data is processed first to detect the layer configuration of the hole (in some embodiments using the method described in Dunford I) and then to detect defects.

[0170] After the measurement data of each complete circumferential scan is processed to identify features in the material stackup, the method performs data analysis to identify any defects within the body of the hole including at edges and at internal material interfaces. Cracks are an example defect, though any suitable type of defect may be targeted for detection. In some embodiments, this data analysis makes use of a shape filter algorithm which is used to locate responses within the scan data that are similar to characteristic shape responses from a stored library of responses. This can be used to highlight and reveal the defect response within noisy inspection data. Shape filtering may be implemented, for example, in ways discussed in Goldfine II, though any suitable shape filtering methodology may be used.

[0171] This data analysis can make use of the identified features of the material stackup. For example, if a shape filtering approach is applied then various features of the material stackup could affect the signature responses selected from the signature library. Such features could include: the material type for each layer, such as identifying each layer as an aluminum alloy or a titanium alloy, and this could be determined by the nominal conductivity of the material within a layer; the thickness of each layer, which could be assessed through the axial variation of the conductivity; and the position of each sense element relative to the edges of the material layers identifying which elements are only over metal without an interface, which elements are near an interface, which elements are over an edge (metal / air interface) or an internal interface (e.g., metal / metal interface potentially with a gap between the metal layers), and which elements are completely off of the metal (e.g., only in air).

[0172] In some embodiments, a more quantitative estimate of the location of each sense element could be performed beyond the simple binary determination of it being either on or off an interface. The lift-off and the responses from multiple sense elements can be used to provide this estimate of the location. This could allow for further refinement of the selection of the appropriate signature responses from the signature library and could allow for corrections of property estimates (such as the electrical conductivity) for sense elements that are near but not yet over a material interface. Note that the actual estimation of the sense element location relative to material edges may not be needed if enough characteristic flaw response shapes are included in the library of signature responses to capture the sensor flaw response variation with proximity to a material edge. In some embodiments, for the purpose of reducing the number of false indications, the data from sense elements over dissimilar metal interfaces could receive additional processing before shape filtering to eliminate large variations in the scan data due to the wandering of the sense element relative to the interface in the axial direction during the course of the circumferential scan. Alternatively, flaw indications from such sense elements could be flagged for further analysis or otherwise suppressed. Additionally, in some embodiments, the lift-off estimates in the local area of each indication could be used to flag indications that correspond to unacceptably high sensor lift-off and so require further analysis or rescanning before making a detection decision.

[0173] Starting with step 806, the method begins a process of repeat scanning of the same hole. At step 806 the method estimates the locations of the defects and anomalies detected in Scan 1. At step 807 a scan plan for each detection is developed such that it provides coverage in the axial and circumferential directions with increased digital resolution, i.e., data points per unit length in the axial and circumferential directions. At step 808 the scanner is moved to the defect / anomaly located closest to the top of the hole. At step 809 rescanning of the defect / anomaly location is performed.

[0174] In some embodiments the rescanning consists of a partial circumferential scan, performed at a higher data rate than Scan 1, that starts far enough before the defect / anomaly to capture the full signature, where the full signature corresponds to the length of the signatures in the signature library that are most appropriate for the identified location. In other embodiments the rescanning consists of a full circumferential scan performed at a slower data rate. In other embodiments, the rescanning consists of a sequence of such circumferential scans with a small axial increment between them, e.g., 0.1 times the sensing element width, to increase the axial digital resolution. In other embodiments, the rescanning consists of a series of repeat circumferential scans performed at the same axial position to improve the signal -to-noise through averaging or to enable other filtering.

[0175] At step 810, if there are more defects / anomalies that were identified in step 806 that have not been rescanned then the scanner is moved (step 811) to the next one located closest to the top of the hole and step 809 is repeated. Otherwise the method proceeds to step 812 where the method differentiates between defects and anomalies using a best match approach to signatures in the signature library. At step 813 the method provides a digital report including estimation of defect size, anomaly type, confidence in the defect detection or anomaly identification, defect / anomaly location, and metadata such as hole location, inspector, and time of inspection. In some embodiments this report provides an estimate of defect length and depth using a correlation table for each defect location.

[0176] In some embodiments, the same hole is scanned with a different set of frequencies and the data is integrated to provide a dataset with more than three frequencies.

[0177] In some embodiments, a sensor array is used to scan the inner surface of a hole in a metal alloy (or a stackup including metal alloys) with the goal of qualifying the metal for a use case. The sensor may be an eddy current array which is scanned over the inner surface of the hole by a hole scanner having two motors - one for axial movement of the sensor and one for circumferential movement of the sensor. The hole may be scanned using a prescribed scan path. The scan data may be analyzed to identify defect-like sensor responses.

[0178] The system records the location of one or more such responses and the sensor rescans the identified locations with higher resolution data. In one such embodiment higher resolution is achieved through slower circumferential scanning. In another such embodiment the axial increment is reduced to provide higher data resolution in the axial direction.

[0179] In another embodiment of this invention anomalies are identified that may be either defects or non-defect anomalies that require different remediation actions than defects. In one such embodiment the defect of interest is a crack and the anomalies are burs, scratches, corrosion pits or other such anomalies that can be repaired more easily or require no action. In one such embodiment, an algorithm is used to differentiate defect anomalies from other anomalies that require different actions using the higher resolution data obtained from a second scan of the anomalies identified in a first scan of the entire internal surface of the hole.

[0180] In another embodiment at least two holes are scanned and digital data from two holes that are in close proximity are used together to enable an improved inspection decision. Close is defined here as being close enough that the responses may be correlated. In one such embodiment the stack-up (layer material types and thicknesses) are the same.

[0181] In one embodiment of this invention, a system comprised of the following elements is used to scan the entire internal surface of a hole, where the system includes: a computer, a graphic user interface implemented in software, a parallel architecture impedance instrument, software for identification of material types, layer thicknesses and the location of defects, an eddy current array sensor, a scanner capable of moving the sensor array across the entire internal surface of a hole where said scanner comprises at least two motors, a library of defect signatures and an algorithm that uses these signatures to enables the software to detect and locate defects in the hole material. In one such embodiment the sensor has at least one larger rectangular conductor that receives current from the electronics and at least two sensing elements for which the electronics measures voltage. In one such embodiment the sensor is mounted on a mandrel that is formed from at least two parts that allow the mandrel diameter to be changed. In another such embodiment the axial position of the sensing elements is adjusted after a first scan of the entire internal surface to position an anomaly detected in a first scan so that the anomaly will be closer to the center of a sensing element when the sensing element moves across the anomaly in a second scan. In another such embodiment the sensor position on a second scan is adjusted relative to an edge using information from the first scan. In one such embodiment the sensing element is adjusted to a prescribed position relative to an edge of an aircraft structure layer so that the neighboring sensing elements and the sensing element positioned at the edge provide an improved capability to detect cracks or suppress anomalies. In one embodiment of this invention a second scan is taken to provide improved capability to estimate the surface length of a crack from two or more sensing element responses. In another such embodiment the crack length and depth are estimated using both the first and second scan data. In another such embodiment only the second scan data is used to estimate the size of the crack.

[0182] The “resolution” of a scan may refer to the positional increment in the relevant scan direction. A relatively small positional increment will result in “higher” resolution while a relatively large increment will result in “lower” resolution. For example, an increment of 0.001 in. may be used. For most bolt hole applications that would represent a high resolution scan. In one such embodiment the sensor position is adjusted vertically to find the edge position using a plunge and then the circumferential scan is taken at the preferred sensing element position. For thin layers on embodiment is taking very high resolution axial data so that the edge effects can allow for improved matches to signatures. This requires high resolution both for the training set and for actual inspections.

[0183] Note that with an array with a 45 degree angle, the effective sensing element height might be 0.021 in. for a 0.03 in. sensing element width, thus for the axial data 21 scans at 0.001 inch axial increments will be needed for the 7x.O21 in. scan width in the vertical direction, and then this repeats for each circumferential scan from the nominal scan method.

[0184] In some embodiments, data is resampled to achieve a specified resolution, for example, in the axial and circumferential directions with a hole. Such resampled data may facilitate easier processing using an artificial neural network, another Al approach, the signature library approach, or any other processing approach whose performance is enhanced by a specified resolution. However, it is likely that a small set of high resolution, medium resolution and nominal resolution resampling values will be sufficient to cover the desired needs for training and testing. In some embodiments, the hardware and software are specifically designed with the intent of providing a digital platform suitable for developers to add Al or machine learning (ML) or other data analytics methodologies, and specifically to develop measurement procedures that can utilize commonly available Al and ML methodologies. In some embodiments, the platform uses fully parallel instrumentation combined with a model based multivariate inverse method that estimates at least liftoff and one additional property at at least one excitation frequency. In some embodiments, the additional property is estimated on a range of test samples with different stackups and defects to enable training of an Al or ML model. In one such embodiment, an inspection method then utilizes the Al or ML model to identify holes with defects. In one such embodiment, the AI / ML model is also trained to estimate the size, location, and type (e.g., corner, midwall) of defect. In one embodiment, the training set includes anomalies of different types such as burs, pits, scratches, out of roundness, chamfers, where the AI / ML training results in a model that captures the difference between the response to such anomalies and the response to defects such as cracks or EDM notches. In some embodiments, the hardware and software are designed to enable users to train and create their own AI / ML models, independent of AI / ML models that may be provided with the system. In one such embodiment, the data is available to users at all levels of analysis and is exportable at all levels of analysis. Tools are also provided to enable comparison of POD and false indication performance for procedures delivered with the system vs procedures (and models) developed by the user. An extension of this approach is to employ Al hardware chips (e.g., available from NVIDIA, AMD) and software (e.g., available Python libraries and proprietary libraries available from vendors such as NVIDIA, AMD, Microsoft) to implement AI / ML training and analysis.

[0185] It may be desirable to maintain a minimum liftoff to avoid false indications, especially at high frequencies caused by edges or inconsistent axial position relative to edges during scanning. By increasing the sensor drive-to-sense gap (distance from drive conductor to the sensing elements) the tolerance for higher liftoff is improved, with a tradeoff for increasing the sensing element effective footprint. The sensor geometry and liftoff range is adjusted in one embodiment to ensure acceptable crack detection performance with acceptable false indication rates. In one such embodiment the desired liftoff range is between 0.007 inches and 0.012 inches for the desired liftoff to meet performance goals. Performance may be stated in terms of a prescribed probability of detection and a prescribed defect size. For example, the performance goal may be a 90% probability of detection with 95% confidence at a comer defect size 0.05 in. by 0.05 in. or a midwall defect size of 0.1 in. by 0.05 in. The liftoff range may be selected based on empirical data data taken at two or more liftoffs (where the liftoff is modified by changing a protective coating thickness on the mandrel, between the sensor and the inspected surface). Empirical data for a range of defect sizes and empirical data for holes without defects for a variety of stackups might be used to determine the POD and the false indication rate for each liftoff value. The empirical data for POD and liftoff might then be used to select a liftoff range that meets the performance goal (POD) and the false indication rate objective. For example, the false indication rate may be 2% or less false indications, where false indications may be counted the number of holes with false indications divided by the total number of holes inspected. Note that in some implementations the false indication will vary with excitation frequency, material type, and layer thicknesses. In these circumstances the liftoff range should be set so that the POD goal and the false indication rate are achieved for all holes to be inspected. For example, if you are inspecting aluminum with no titanium in the stack up and all layers are relatively thick (e.g., at least 5 times larger than the sensing element width), then a lower liftoff range may be acceptable since the false indication rate may not be as sensitive to liftoff. In this case, lower excitation frequencies may be selected to further improve the false indication rate without reducing the POD significantly.

[0186] Section VI - Closing Discussion

[0187] Having thus described several aspects of at least one embodiment of this invention, it is to be appreciated that various alterations, modifications, and improvements will readily occur to those skilled in the art.

[0188] Such alterations, modifications, and improvements are intended to be part of this disclosure, and are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description and drawings are by way of example only.

[0189] The above-described embodiments of the present invention can be implemented in any of numerous ways. For example, the embodiments may be implemented using hardware, software or a combination thereof. When implemented in software, the software code can be executed on any suitable processor or collection of processors, whether provided in a single computer or distributed among multiple computers.

[0190] Further, it should be appreciated that a computer may be embodied in any of a number of forms, such as a rack-mounted computer, a desktop computer, a laptop computer, or a tablet computer. Additionally, a computer may be embedded in a device not generally regarded as a computer but with suitable processing capabilities, including a Personal Digital Assistant (PDA), a smartphone or any other suitable portable or fixed electronic device.

[0191] Also, a computer may have one or more input and output devices. These devices can be used, among other things, to present a user interface. Examples of output devices that can be used to provide a user interface include printers or display screens for visual presentation of output and speakers or other sound generating devices for audible presentation of output. Examples of input devices that can be used for a user interface include keyboards, and pointing devices, such as mice, touch pads, and digitizing tablets. As another example, a computer may receive input information through speech recognition or in other audible format.

[0192] Such computers may be interconnected by one or more networks in any suitable form, including as a local area network or a wide area network, such as an enterprise network or the Internet. Such networks may be based on any suitable technology and may operate according to any suitable protocol and may include wireless networks, wired networks or fiber optic networks.

[0193] Also, the various methods or processes outlined herein may be coded as software that is executable on one or more processors that employ any one of a variety of operating systems or platforms. Additionally, such software may be written using any of a number of suitable programming languages and / or programming or scripting tools, and also may be compiled as executable machine language code or intermediate code that is executed on a framework or virtual machine.

[0194] In this respect, the invention may be embodied as a computer readable medium (or multiple computer readable media) (e.g., a computer memory, one or more floppy discs, compact discs, optical discs, magnetic tapes, flash memories, circuit configurations in Field Programmable Gate Arrays or other semiconductor devices, or other tangible computer storage medium) encoded with one or more programs that, when executed on one or more computers or other processors, perform methods that implement the various embodiments of the invention discussed above. The computer readable medium or media can be transportable, such that the program or programs stored thereon can be loaded onto one or more different computers or other processors to implement various aspects of the present invention as discussed above.

[0195] In this respect, it should be appreciated that one implementation of the above-described embodiments comprises at least one computer-readable medium encoded with a computer program (e.g., a plurality of instructions), which, when executed on a processor, performs some or all of the above-discussed functions of these embodiments. As used herein, the term “computer-readable medium” encompasses only a computer-readable medium that can be considered to be a machine or a manufacture (i.e., article of manufacture). A computer-readable medium may be, for example, a tangible medium on which computer-readable information may be encoded or stored, a storage medium on which computer-readable information may be encoded or stored, and / or a non-transitory medium on which computer-readable information may be encoded or stored. Other non-exhaustive examples of computer-readable media include a computer memory (e.g., a ROM, a RAM, a flash memory, or other type of computer memory), a magnetic disc or tape, an optical disc, and / or other types of computer-readable media that can be considered to be a machine or a manufacture.

[0196] The terms “program” or “software” are used herein in a generic sense to refer to any type of computer code or set of computer-executable instructions that can be employed to program a computer or other processor to implement various aspects of the present invention as discussed above. Additionally, it should be appreciated that according to one aspect of this embodiment, one or more computer programs that when executed perform methods of the present invention need not reside on a single computer or processor, but may be distributed in a modular fashion amongst a number of different computers or processors to implement various aspects of the present invention.

[0197] Computer-executable instructions may be in many forms, such as program modules, executed by one or more computers or other devices. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Typically the functionality of the program modules may be combined or distributed as desired in various embodiments.

[0198] Also, data structures may be stored in computer-readable media in any suitable form. For simplicity of illustration, data structures may be shown to have fields that are related through location in the data structure. Such relationships may likewise be achieved by assigning storage for the fields with locations in a computer-readable medium that conveys relationship between the fields. However, any suitable mechanism may be used to establish a relationship between information in fields of a data structure, including through the use of pointers, tags or other mechanisms that establish relationship between data elements.

[0199] Various aspects of the present invention may be used alone, in combination, or in a variety of arrangements not specifically discussed in the embodiments described in the foregoing and is therefore not limited in its application to the details and arrangement of components set forth in the foregoing description or illustrated in the drawings. For example, aspects described in one embodiment may be combined in any manner with aspects described in other embodiments.

[0200] Also, the invention may be embodied as a method, of which an example has been provided. The acts performed as part of the method may be ordered in any suitable way. Accordingly, embodiments may be constructed in which acts are performed in an order different than illustrated, which may include performing some acts simultaneously, even though shown as sequential acts in illustrative embodiments.

[0201] For the purposes of describing and defining the present disclosure, it is noted that terms of degree (e.g., “substantially,” “slightly,” “about,” “comparable,” etc.) may be utilized herein to represent the inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. Such terms of degree may also be utilized herein to represent the degree by which a quantitative representation may vary from a stated reference (e.g., about 10% or less) without resulting in a change in the basic function of the subject matter at issue. Unless otherwise stated herein, any numerical values appeared in this specification are deemed modified by a term of degree thereby reflecting their intrinsic uncertainty. The “substantially simultaneous response” means responses measured within 1 second of one another.

[0202] Use of ordinal terms such as “first,” “second,” “third,” etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements.

[0203] Also, the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or “having,” “containing,” “involving,” and variations thereof herein, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items.

Claims

CLAIMSWhat is claimed is:

1. A scanner for controlling a removable element, the scanner comprising: a housing; a first motor secured within the housing for actuating circumferential motion for the mandrel; a second motor within the housing for actuating axial motion for the element; a geartrain comprising a plurality of gears; and a plurality of shafts for maintaining alignment of the geartrain, wherein the housing provides structural support for the plurality of shafts.

2. The scanner of claim Cl, further comprising: a first encoder to record a circumferential position of the element; and a second encoder to record an axial position of the element.

3. The scanner of claim Cl, further comprising a solenoid to further control the element.

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